1. Field of the Invention
The present invention relates to a novel tape reel locking and releasing device for use in a tape cassette and, more particularly, to a mechanism for achieving an exact operation of locking and releasing a pair of tape reels.
2. Description of the Prior Art
It is generally customary in a tape cassette that, for the purpose of preventing any slackening of a tape during storage or transport, there is provided a reel locking device capable of inhibiting undesired rotation of tape reels around which the tape is wound.
An exemplary reel locking device of such type is equipped with a slide member which is so disposed as to be movable between a lock position and a release position and is resiliently urged toward the lock position. A known example is concerned with a tape cassette employed in an 8-mm VCR (video cassette recorder) or the like as disclosed in U.S. Pat. No. 4,579,295.
A conventional reel locking/releasing device a of such type is shown in FIG. 9A, 9B and 10.
A slide member b is shaped into a block with a recess c open at a bottom surface thereof. A lower portion e under an intermediate region of a back surface d of such recess c is formed into an inclined plane which is displaced backward as it extends downward. A compression coil spring h is provided between the slide member b and a back wall g of a cassette case f to apply a resilient force for moving the slide member b forward.
The slide member b has a lock element (not shown) which is brought into engagement with teeth (not shown) of a tape reel when the slide member b is moved forward, thereby locking the tape reel to prevent its rotation.
An insertion aperture i is formed in a bottom wall j of the cassette case f, and the recess c formed in the slide member b opens to the outside of the cassette case f through such aperture i.
For releasing the tape reel from the locked state in the reel locking/releasing device a, there are the following two methods.
According to the first method, as illustrated in FIG. 9(A), a release pin k provided in a tape player is inserted into the recess c in the slide member b through the aperture i when the tape cassette is loaded at a predetermined position in the tape player. Subsequently, as illustrated in FIG. 9(B), the release pin k is shifted backward to press the back surface d of the recess c, whereby the slide member b is moved backward to release the tape reel.
According to the second method, as illustrated in FIG. 10, a release pin 1 provided in a tape player is inserted vertically upward into the recess c in the slide member b through the aperture i when the tape cassette is loaded at a predetermined position, and during such inserting operation, the top end of the release pin 1 butts against the inclined plane e of the recess c, whereby the inclined plane e is pressed relatively backward. Consequently the slide member b is moved backward to release the tape reel from the locked state.
In the conventional reel locking/releasing device a for a tape cassette shown in FIGS. 9A, 9B and 10, there may occur an occasion where the locking action is rendered uncertain or the locked reel fails to be completely released.
In the method of FIG. 10, the shift of the slide member b caused by butting of the release pin 1 against the inclined plane e may be insufficient in length, so that the locked reel may fail to be completely released. Furthermore, if the structure is so modified as to attain a completely unlocked state, the locking action may be rendered incomplete to the contrary.
For realizing a greater length of such shift, there may be contrived a means to lengthen the inclined plane by extending the plane up to a higher position or by increasing the gradient of the plane.
However, since the length of projection of the release pin 1 into the cassette case f is limited, it is practically difficult to adopt the above method of extending the inclined plane up to a higher position. And if the gradient of the inclined plane is increased, the slidability between the release pin 1 and the inclined plane e is deteriorated to consequently bring about an improper operation.